Ah, I just upgraded from RX580 to 6600XT and haven't had any freezes so far. On RX580 I sometimes had games that managed to freeze the system complete with random pixel noise and VRAM fragments shown on screen for seconds before it rebooted, but that was a long time back and only on bleeding-edge Mesa and Proton Experimental so my own fault.
Mesa 22 and 23 have been great so far. Maybe the firmware got more stable as well (I'm on Debian). I'd definitely recommend an RDNA2 card over any Nvidia today despite some of these hiccups.
The GTX 1070 in my other machine has given me more headaches (kernel modules not compatible with newer kernels, random Vulkan issues resulting in broken shaders showing nonsense like sparkles or black areas, etc.).
What were some of the positives and negatives? Me personally, I have an RDNA2 card and got bitten by the gamma being too dark on hardware cursors (now resolved) and memory clock stuck at 1 GHz with some refresh rates (workaround is not to use refresh above ~144 Hz).
I've been using imap-backup for many years without issue, it backs up to mbox files that it can restore onto any IMAP server because it also stores IMAP metadata on the side. I then backup the dir itself using borg. It deduplicates and compresses so the backup archives themselves are extremely small.